The present invention relates to a vibratory gyro-sensor that uses the Coriolis force.
Tuning fork vibratory gyro-sensors that use the Coriolis force are widely used as sensors for detecting the rotation of objects. In particular, flatly supported tuning fork vibratory gyro-sensors are used in a wide variety of applications, e.g., vibration prevention in cameras and car navigation systems, due to the ease with which they can be designed in a thin, compact manner.
In recent years, there has been research into the use of flatly supported tuning fork vibratory gyro-sensors for vehicle control applications. Vehicle control can affect the safety of a vehicle and can be a critical, life-or-death application. As a result, vibratory gyro-sensors used for this type of application must provide high precision, with good vibration and shock resistance.
A conventional flatly supported tuning fork vibratory gyro-sensor is described in “Experimental Investigation of Flatly Supported Vibratory Gyro-Sensor Using Quartz Crystal Trident-Type Tuning Fork Resonator” (N. Shiratori, Y. Tomikawa, and K. Onishi, Transducers '99, No. 3P2.26, pp. 82-85 (1999)). The prior art gyro-sensor described in this document is a type known as a trident tuning fork vibratory gyro-sensor. Generally, trident tuning fork vibratory gyro-sensors form a cantilevered support structure, where three tuning fork arms are secured at one end with the other end free.
Japanese laid-open patent publication number Hei 11-281372 also describes a flatly supported tuning-form vibratory gyro-sensor. In this tuning fork vibratory gyro-sensor, the vibrator is supported at one point at its center of gravity.
The two references describe that the support structures in conventional flatly supported tuning fork vibratory gyro-sensors take the form of single-point support or cantilevered support.
However, with single-point support or cantilevered support used in conventional flatly supported tuning fork vibratory gyro-sensors, the area of the attachment section is small. As a result, if vibration or impact is applied from outside, the vibration or impact can tend to concentrate on the support section. The prior art supports make it possible for the sensor to be damaged in severe conditions, e.g., in a moving vehicle, where many vibrations and impacts occur over a long period of time. Also, if the sensor is formed in a compact design overall, impact tends to concentrate further at the support section.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.